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Li4Ti5O12/N-Doped Graphene Microspheres As High Rate Anode Materials for Lithium Ion Batteries

Monday, 20 June 2016
Riverside Center (Hyatt Regency)

ABSTRACT WITHDRAWN

Spinel Li4Ti5O12(LTO) has been demonstrated to be one of the most promising electrode materials for lithium-ion batteries due to flat voltage range (1.55V vs. Li/Li+), high reversible capacity (175 mAhg-1), and good cyclability during charge/discharge processes.

However, the electrochemical performance of LTO deteriorates with increasing charge/discharge rates due to its low electronic conductivity (10-9 Scm-1). Several strategies, such as particle size reduction to nanoscale, metal doping, surface modification and carbon coating, and formation of composite with carbonaceous materials, have been developed to enhance the electrochemical performance.

Especially, metal oxide with carbonaceous materials provides a high electrical conductivity, which can allow lithium ions and electrons to have an access readily to reaction sites of the metal oxide. Compared to other carbonaceous materials such as graphite, carbon black, and carbon nanotube, graphene a single layer of carbon atoms tightly packed in to a 2-dimensional honeycomb sp2 carbon lattice, has attracted a rapidly growing research interest owing to high conductivity (104 Scm-1), high surface area (2630 m2g-1) and good mechanical properties. Additionally, the electrical conductivity of graphene could be modified by nitrogen doping.

As mentioned above, LTO has poor electronic conductivity. Herein, we describe a novel strategy for the fabrication of LTO/N-doped Graphene microsphere composite by spray-drying method and annealing process. It makes micro N-graphene microsphere stuffed with LTO particles. The key strategy is to create a network between N-graphene and LTO particles, and the N-graphene can be embedded into the LTO materials to greatly improve the surface conductivity. The reversible capacity, especially rate performance of the LTO/N-doped Graphene microsphere in comparison with the bare LTO and LTO/graphene microspheres were evaluated.

Experimental results indicate that the LTO/N-doped Graphene microsphere can indeed deliver enhanced rate capability and good cyclic stability. Detailed synthetic procedure and electrochemical properties of LTO/N-doped Graphene microsphere will be presented at the meeting.